Classification of Magnetosheath Jets Using Neural Networks and High Resolution OMNI (HRO) Data

Savvas Raptis,Martin Lindberg,Tomas Karlsson,Sigiava Aminalragia-Giamini

doi:10.3389/fspas.2020.00024

Savvas Raptis, Martin Lindberg + Show 2 more

Open Access

https://doi.org/10.3389/fspas.2020.00024

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Abstract

Magnetosheath jets are transient, localized dynamic pressure enhancements found downstream of the Earth's bow shock in the magnetosheath region. Using a pre-existing database of magnetosheath jets we train a neural network to distinguish between jets found downstream of a quasi-parallel bow shock θBn 45). The initial database was compiled using MMS measurements in the magnetosheath (downstream) to identify and classify them as "quasi-parallel" or "quasi-perpendicular", while the neural network uses only solar wind (upstream) measurements from the OMNIweb database. To evaluate the results, a comparison with three physics-based modeling approaches is done. It is shown that neural networks are systematically outperforming the other methods by achieving a ~93 agreement with the initial dataset, while the rest of the methods achieve around 80%. The better performance of the neural networks likely is due to the fact that they use information from more solar wind quantities than the physics-based models, even in the absence of certain upstream properties, such as IMF direction.

Highlights

The main goal of this study is to classify jets between those originating from quasi-parallel shock transitions and those originating from quasi-perpendicular ones
There is a variety of methods based on the coplanarity theorem (e.g., Paschmann and Daly, 1998)
After establishing the advantage of the neural network method when providing the upstream magnetic field vector (Bu), we investigate the performance of Neural Networks (NN) even in the absence of the, in principle, vital information of the magnetic field orientation

Summary

Introduction

There are phenomena too complex to be precisely described by the current theoretical framework This complexity arises mainly from the geometry of the bow shock and the rapid changes in the Interplanetary Magnetic Field (IMF). A phenomenon that is generated in the interaction of the solar wind with the bow shock is the so called “magnetosheath jet.”. These jets are usually described as localized enhancements of dynamic pressure in the magnetosheath plasma and are attributed to a velocity or a density increase or in most cases an increase of both (e.g., Amata et al, 2011; Archer et al, 2012; Plaschke et al, 2018) A phenomenon that is generated in the interaction of the solar wind with the bow shock is the so called “magnetosheath jet.” These jets are usually described as localized enhancements of dynamic pressure in the magnetosheath plasma and are attributed to a velocity or a density increase or in most cases an increase of both (e.g., Amata et al, 2011; Archer et al, 2012; Plaschke et al, 2018)

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